1. Field of the Invention
The present invention relates to an optical device or instrument with a bayonet mount coupling and position restriction means.
2. Description of the Prior Art
The bayonet mount coupling provides an advantage that an optical device with a bayonet mount can be attached to another complementary optical device with a compensating bayonet mount, with little relative rotation. However, the bayonet mount coupling is provided with a position restricting means because the coupling between the devices will be unstable if their relative angular positions are not restricted.
Heretofore, there have been known two types of the position restricting means. One of them is of the radially inwardly operating type, while the other is of the optical axis direction operating type. In each position restriction type, some kinds of optical device may be made interchangeable with one another by standardizing the configurations, structures and the like of their coupling portions insofar as they are of the same position restriction type. However, interchangeability could not be expected between optical devices whose position restriction type is different from each other. That is, an optical device of one position restriction type could not be coupled with an optical device of the other position restriction type. Thus, adaptability has been limited for two complementary optical devices to be used in coupled relationship with each other, e.g. an interchangeable lens and a camera body.